This FIRCA application entitled "Glia-neuron interaction" represents a new direction for the Parent Grant. The focus of the proposed project is to test the hypothesis that glia support expression of ion channels and receptors in neurons. The studies will focus on the functional expression of glutamate receptors in cultured central neurons and chemically gated channels in sensory neurons. In collaboration with the P.I. at the Institute of Neurobiology in San Juan, Dr. Vyklicky has demonstrated the diversity of chemically gated channels in the DRG neurons of the frog in short-term culture and has analyzed physiological properties of the inward rectifying potassium channels in cultured glia isolated from the frog optic nerve. This FIRCA proposes to study the possible involvement of glia in (1) the mechanisms of functional expression of the capsaicin and of GABA-A receptors in sensory neurons and (2) of the glutamate receptors with emphasis on NMDA receptors in cultured central neurons. This project complements the long-lasting interest of the P.I. in the mechanisms of neuron-glia interaction. It focuses on the trophic effects of glia on the ligand gated ionic channels in neurons which may participate in plastic changes in synaptic transmission or subserve different modalities of sensation including pain.